In addition to bores, internal threads are central inspection characteristics of workpieces, particularly in the drivetrain of motor vehicles. Typically, internal threads are often used at safety and functionally relevant points in the drivetrain, for example in the region of the wheel attachments, cylinder heads, et cetera.
Whereas screws are inspected by means of, for example, the silhouette procedure in respect of the thread dimensions thereof, internal threads are characterized not only by the thread dimensions, but also by the position and orientation of the internal thread relative to the workpiece.
The inspection of thread dimensions of internal threads has until now been carried out by way of occasional checks by means of thread gauges, capacitive sensors or interference-microscopic methods. However, the position and/or the orientation of the internal thread relative to the workpiece is not measured herein and therefore not inspected.